11 thoughts on “The MIT App Inventor Support Forum”

  1. Can someone help with this please
    How can I get this formula to work in app inventor2
    =(LN (11.68402337/?)/(LN (1.1229283027)))-3

    ?= Is input of a textbox


    1. I just got back from a camping trip without Internet access.

      In the Blocks editor, drag one of the math blocks, such as Square Root to the editor canvas. Then click on the square root V downarrow and select LOG. I think this is natural log but have not used it myself.

      To reference the textbox input, let’s say your textbox is named txtInputValue. Click on the txtInputValue component in the Blocks editor list of components (below Screen1)and look for where it says txtInputValue.Text – drag that into your arithmetic expression blocks. The number in the text box will automatically convert to a numeric value.

      I should create a math tutorial – that would be a good idea!



  2. Hello!
    Here is what i am trying to to: I want my phone to send a text to a Bluetooth dongle, whenever a certain file or folder are opened. I think i is supposed to use the .AfterFileSaved control block? but i’m not sure about it…

    My problem is double:
    1. I don’t seem to find the right blocks for the task.
    2. The whole thing with getting the right file paths, seems confusing to me.

    Can anyone help me please?



    1. Start here for Bluetooth
      And follow the links in that poster to my Bluetooth tutorials.

      Here is a “cheat sheet” for text files

      Here is a tutorial basic text files

      Finally, volume 3 of my App Inventor e-book series
      App Inventor Databases and Files: TinyDB, TinyWebDB, Fusion Tables and Files

      The file paths, in terms of where files are located on your device, is confusing. The tutorial above has information on that, and some tools that may help you locate the files on your device.



  3. Hello! Is it possible to make a timed sound recording such that once the screen is intitalized, the voice recorder turns on and automatically goes of after a minute, then saves the recording on TinyDB without having to use any buttons?


    1. Kind of – use a Clock timer (in the Sensors section). Set the interval to 1 minute. Set the enabled property to false to turn off the clock timer.

      Use event handlers for:
      – when initialized, activate your voice recorder.
      – in the initialization, set the clock to enabled
      – in the Clock event handler for Timer, turn off the recorder
      – Process the voice recording.

      I have not used the voice recorder and I do not know if you can store its data in the TinyDB, but definitely worth a try.



      1. Thanks for the input! I got it to work but apparently the player component is ‘Unable to load’. I’m not sure why it won’t play. I’ve confirmed that it is fetching the fight files from TinyWebdb, with the right file name and url, but it isn’t playing them.


  4. Hi, is it possible using app inventor to create an event for an app to automatically cut or trim a long video into tiny portions


    1. Not that I know of. App Inventor is very limited in its support of video media. I do imagine this will change in the future, as MIT released a preliminary component development kit that enables 3rd party developers to add new features to MIT App Inventor. But for now, I don’t think we could do video cutting in App Inventor … Ed


    1. Probably not, for a couple of reasons.

      App Inventor does have a Player component that plays MP3 files – but, the MP3 file has to be included inside the app’s package file as a “resource”. This means two limits: (1) you have to preset the file inside the app, and (2) the maximum app size is limited and you will likely use up the maximum app memory with very few MP3 files.

      The second reason depends on how you got your music into iTunes. If you recorded or ripped your own mp3 files, then iTunes will store regular mp3 files. But if you bought music from iTunes, then it is probably stored in .m4a or .m4p format, the latter of which is a copy protected format that can only be played in itunes. The App Inventor player can only play unprotected mp3 files.



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